Address/latitude and longitude converting device and geographical information system using the same

ABSTRACT

By converting address information  200  input to a geocoding unit  10  into a tree structure formed hierarchically in an administrative district, generating address tree information obtained by associating latitude and longitude information with at least a node of the lowest layer in each branch of the tree structure and storing the address tree information thus generated in a high-speed accessible memory  14  to proceed a retrieval while tracing the address tree information in order from a parent node to a child node to narrow down a retrieval range, it is possible to efficiently search latitude and longitude information corresponding to given address information therefrom and to perform a retrieval at a higher speed as compared with the related art in which access is given to a conversion table stored in a disk.

TECHNICAL FIELD

The present invention relates to an address/latitude and longitudeconverting device and a geographical information system using the sameand more particularly is suitably used for an address/latitude andlongitude converting device for converting geographical informationabout an address into coordinate information about a latitude andlongitude and a geographical information system for performing apredetermined processing by using latitude and longitude informationconverted by the address/latitude and longitude converting device.

BACKGROUND ART

Conventionally, there is known the technology for convertinggeographical information such as an address or a place name intocoordinate information about a latitude and longitude (for example, seePatent Documents 1 and 2). The technology is referred to as geocodingand is widely used practically in an application using a map. Forexample, there is provided a system obtained by combining the geocodingand the geographical visualizing technology referred to as GIS(Geographic Information System). According to the system of this type,for example, values linked to addresses in a database, totalizationresults thereof or the like can be displayed to be easily understoodvisually in a corresponding position on a map based on a latitude andlongitude converted from the address.

Referring to the information processing device described in the PatentDocument 1, address book information and latitude and longitudeinformation acquired based on the address information are stored as aconversion table corresponding to each other, and a latitude andlongitude of the position is obtained from a prefecture, a city, a townand a street of the address information by utilizing the conversiontable. Map image information is retrieved based on the latitude andlongitude information and is synthesized with the address bookinformation, and an address book or a current position is displayed.

The information processing device described in the Patent Document 1stores, in the conversion table, latitude and longitude informationabout a spot corresponding to an address according to a hierarchicalstructure of “prefecture•city•town•street”. Even if an address to beinput is not complete like “1-chome, Yoshidacho, Totsuka-ku,Yokohama-shi, Kanagawa-ken” but only a high order hierarchy such as“Yokohama-shi, Kanagawa-ken” or “Totuka-ku, Yokohama-shi, Kanagawa-ken”,it is possible to obtain coordinates of spots corresponding torespective addresses.

Referring to the coordinate imparting system described in the PatentDocument 2, moreover, a latitude and longitude database causing anaddress and position coordinates to correspond to each other is preparedand the position coordinates corresponding to the input address areretrieved from the database. In the retrieval, by narrowing positioncoordinates every hierarchy based on an administrative district, it ispossible to perform the retrieval while compensating for theimperfection of the input address information every hierarchy.Consequently, it is possible to enhance retrieval accuracy.

Patent Document 1: Japanese Laid-Open Patent Publication No. 1996-50594

Patent Document 2: Japanese Laid-Open Patent Publication No. 2003-223453

DISCLOSURE OF THE INVENTION

In recent years, API (Application Programming Interface) for performingthe geocoding described above is provided and address information can beconverted into latitude and longitude information by utilizing the API.Referring to the conventional geocoding using the API, however, there isa problem in that a conversion speed is very low, such as several casesto several tens cases per second and a long time is taken for aprocessing. For this reason, if the latitude and longitude informationis converted from the address information by the geocoding when arequest is given from an application for performing some processing byutilizing the latitude and longitude information, a response time takento display a result after giving the request is increased.

For example, in the case in which data having addresses in an areadesignated by a user is to be visualized and displayed visually byvisualization software by taking, as a target, a database having anenormous number of data stored from a business system or the like, avery long time is required for visualizing and displaying data in thedesignated area. When a large number of data are included in thedesignated area, a time of several tens minutes to several hours issometimes required for converting the address information into thelatitude and longitude information by the geocoding, resulting in verypoor operability.

In order to avoid the inferiority in a response, conventionally, all ofthe address information stored in the database are previously convertedinto the latitude and longitude information by the geocoding to generatean intermediate table, and the intermediate table is referred to,thereby performing a processing corresponding to a request given from anapplication if any.

In this case, however, it is necessary to activate the geocoding,thereby maintaining the intermediate table when new data is registeredin the database or existing data is updated. Conventionally, themaintenance is performed by a batch processing. For this reason, thereis a problem in that data registered newly in the database or datahaving an address changed cannot be utilized by referring to a positionfrom an application until the maintenance of the intermediate table iscompleted.

The present invention has been made in order to solve the problems andhas an object to enable conversion from address information intolatitude and longitude information at a high speed in real timedepending on a request given from an application utilizing the latitudeand longitude information without generating an intermediate tablerequiring maintenance by a batch processing.

In order to attain the object, an address/latitude and longitudeconverting device according to the present invention serves to convertinput address information into a tree structure formed hierarchically inan administrative district, to generate address tree informationobtained by associating latitude and longitude information with at leastnodes of the lowest layer in each branch of the tree structure, and tostore the generated address tree information in a high-speed accessiblememory.

According to the present invention having the structure described above,information to be used for converting the address information into thelatitude and longitude information is not prepared in a form of aconventional conversion table obtained by causing each address and eachlatitude and longitude to perform one-to-one correspondence to eachother but a form of the tree structure and is stored in the high-speedaccessible memory. When actually converting the address information intothe latitude and longitude information, therefore, it is possible toefficiently search the latitude and longitude information correspondingto the given address information therefrom by proceeding a retrievalwhile tracing the address tree information of the tree structure inorder from a parent node to a child node to narrow down a retrievalrange. In addition, in the present invention, the address treeinformation is stored in the high-speed accessible memory. As comparedwith the related art in which access is given to a conversion tablestored in a disk, therefore, it is possible to perform a retrieval at ahigh speed.

From the foregoing, even if the conversion from the address informationinto the latitude and longitude information is performed when a requestfrom an application utilizing the latitude and longitude information isgiven, the conversion can be completed in a very short time. Therefore,it is possible to implement remarkably high response performance.Consequently, it is not necessary to previously generate an intermediatetable in order to avoid inferiority in a response as in the related art.According to the present invention, thus, it is possible to perform theconversion from the address information into the latitude and longitudeinformation at a high speed in real time depending on the request givenfrom the application utilizing the latitude and longitude informationwithout generating the intermediate table requiring maintenance by abatch processing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an example of a structure of a geographicalinformation system executing an address/latitude and longitudeconverting device according to the present embodiment.

FIG. 2 is a diagram typically showing a part of address tree informationto be generated by an address tree information generating unit accordingto the present embodiment.

FIG. 3 is a diagram typically showing a part of index information to begenerated by an index information generating unit according to thepresent embodiment.

FIG. 4 is a diagram typically showing a state in which the indexinformation and the address tree information are associated with eachother through pointers according to the present embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described below withreference to the drawings. FIG. 1 is a diagram showing an example of astructure of a geographical information system executing anaddress/latitude and longitude converting device according to thepresent embodiment. As shown in FIG. 1, a geographical informationsystem 100 according to the present embodiment includes a geocoding unit10 and an application unit 20.

The geocoding unit 10 serves to convert address information intolatitude and longitude information and is configured from a serverdevice, for example. The geocoding unit 10 includes an addressinformation input unit 11, an address tree information generating unit12, an index information generating unit 13 and a memory 14. Each offunctional blocks of the address information input unit 11, the addresstree information generating unit 12 and the index information generatingunit 13 is configured from software installed in a server device, forexample.

In other words, each of the functional blocks 11 to 13 actually includesa CPU, an RAM, an ROM and the like in a computer and is implemented byoperating a program stored in a recording medium such as the RAM, theROM, a hard disk, a semiconductor memory or the like. The server devicehaving the geocoding unit 10 is equivalent to the address/latitude andlongitude converting device according to the present invention. A partor whole of the respective functional blocks 11 to 13 can also beconfigured from hardware or a DSP (Digital Signal Processor).

The application unit 20 serves to perform a predetermined applicationprocessing by using the latitude and longitude information convertedfrom the address information through the geocoding unit 10 and isconfigured from a server device, for example. The application unit 20includes a request acquiring unit 21, a latitude and longitudeinformation acquiring unit 22, a processing executing unit 23, aprocessing result transmitting unit 24 and a database 25.

Each of functional blocks of the request acquiring unit 21, the latitudeand longitude information acquiring unit 22, the processing executingunit 23 and the processing result transmitting unit 24 is configuredfrom software installed in the server device, for example. The softwareis visualization software through the GIS, for example, and valueslinked to addresses and stored in the database 25, totalization resultsthereof or the like can be displayed to be easily understood visually ina corresponding position on a map based on the latitude and longitudeconverted from the address.

The respective functional blocks 21 to 24 actually include a CPU, anRAM, an ROM and the like in a computer and are implemented by operatinga program stored in a recording medium such as the RAM, the ROM, a harddisk, a semiconductor memory or the like. Apart or whole of therespective functional blocks 21 to 24 can also be configured fromhardware or a DSP.

The geocoding unit 10 and the application unit 20 (both of the serverdevices) are connected to each other by an LAN, for example, and canmutually transmit/receive data. Moreover, the application unit 20 isconfigured to be connectable to a user terminal 30 through acommunication network 300 such as internet. The user terminal 30transmits a request to the application unit 20 depending on a useroperation, thereby causing the application unit 20 to execute adesirable processing, and can obtain a result of the processing anddisplay the result on a screen.

Although the description has been given to the structure in which theseparate server devices include the geocoding unit 10 and theapplication unit 20 respectively with reference to FIG. 1, the presentinvention is not restricted to this configuration. For example, it isalso possible to employ a structure in which a single server deviceincludes the geocoding unit 10 and the application unit 20. Moreover,the functions of the address information input unit 11, the address treeinformation generating unit 12 and the index information generating unit13 in the geocoding unit 10 and those of the latitude and longitudeinformation acquiring unit 22 and the processing executing unit 23 inthe application unit 20 may be implemented by software installed in theuser terminal 30.

The address information input unit 11 of the geocoding unit 10 inputsaddress information 200 from an outside. The address information 200 isthe same as address information stored in the database 25 of theapplication unit 20. For example, the address information 200 can beconstituted by a CSV file output from the database 25. Alternatively,the address information input unit 11 maybe configured to directly inputthe address information from the database 25 of the application unit 20.In this case, a configuration for inputting the address information 200is not restricted to a configuration of the CSV file.

The database 25 stores one or more data having at least an address as anitem. Items other than the address are arbitrary. Data to be stored inthe database 25 may be any of client business card data, company salesdata, various statistical data and the like and their types and contentsdo not matter. In the case in which the data is output from the database25 to constitute the address information 200, it is sufficient thatthere is at least information about an item of an address andinformation about the other items are not required. Although the exampleof FIG. 1 shows the structure in which the application unit 20 includesthe database 25, the database 25 may be provided on the outside of theapplication unit 20 (the server device).

The address tree information generating unit 12 converts the addressinformation 200 input by the address information input unit 11 into atree structure formed hierarchically in an administrative district andgenerates address tree information obtained by associating latitude andlongitude information with at least nodes of the lowest layer in eachbranch of the tree structure. Then, the address tree information thusgenerated is stored in the high-speed accessible memory 14. Thehigh-speed accessible memory 14 is referred to as a main storage deviceor a primary storage device and can read/write data at a higher speed(approximately 100000 times) as compared with a disk type storage devicereferred to as an auxiliary storage device or a secondary storagedevice.

FIG. 2 is a diagram typically showing a part of the address treeinformation to be generated by the address tree information generatingunit 12. As shown in FIG. 2, with a configuration in which a firsthierarchy (a top layer) is set to be a root node, a second hierarchy isset to be a prefecture, a third hierarchy is set to be a ward or amunicipality, a fourth hierarchy is set to be the municipality or theward, and a fifth hierarchy or less is set to be a residence indication(a block mark and a house number) or a lot number, the addressinformation 200 is converted into a tree structure formed hierarchicallyby an administrative district. Then, the latitude and longitudeinformation corresponding to positions of the block mark and the housenumber are associated with nodes of the lowest layer in each branch ofthe tree structure (a node related to the residence indication or thelot number) to constitute the address tree information.

By associating the latitude and longitude information with the nodes ofthe lowest layer, it is possible to associate the latitude and longitudewith a perfect address such as “20-1, Sakuragaokacho, Shibuya-ku,Tokyo-to”. In contrast, the latitude and longitude information may befurther associated with a node of a high order hierarchy. Consequently,a latitude and a longitude can be associated with an imperfect addresssuch as “Shibuya-ku, Tokyo-to” or “Sakuragaokacho, Shibuya-ku,Tokyo-to”. Even if the perfect address is not stored in the database 25,thus, the imperfect address information can be converted into latitudeand longitude information corresponding to that position.

The index information generating unit 13 generates index informationconstituted by each name allocated to each node of each hierarchy in theaddress tree information generated by the address tree informationgenerating unit 12 (a name of a prefecture or a municipality, a blockmark, a home number, a lot number or the like) and each pointer from theeach name to each node of each hierarchy in the address treeinformation. Then, the index information thus generated is stored in thememory 14.

The address information 200 includes an imperfect address starting withthe second hierarchy of the address tree information such as “. . .Shibuya-ku” as well as a perfect address starting with the firsthierarchy of the address tree information such as “. . . Shibuya-ku,Tokyo-to”. For either of the addresses, the address tree informationgenerated by the address tree information generating unit 12 needs to beretrievable. Moreover, it is necessary to handle words of approximately200000 names. For this reason, it is preferable that a word can beretrieved at a high speed in a memory-saving manner.

In the present embodiment, therefore, the index information generatingunit 13 generates index information having a tree structure shown inFIG. 3. FIG. 3 is a diagram typically showing a part of the indexinformation to be generated by the index information generating unit 13.As shown in FIG. 3, the index information is constituted by representinga plurality of names to be allocated to respective nodes of respectivehierarchies in the address tree information as a tree structure formedhierarchically character by character and associating pointers from thenodes of the lowest layer in each branch of the tree structure tocorresponding nodes in the address tree information with the nodes.

For example, both a name of “Tokyo-to” and a name of “Togocho” are wordsstarting with “To”. In this case, there is generated index informationhaving a tree structure in which a first hierarchy is set to be a rootnode, a second hierarchy is set to be “To”, a third hierarchy is set tobe “kyo” and “go”, and a fourth hierarchy is set to be “to” and “cho”. Acharacter of “To” which is common to two words is shared by the firsthierarchy. The pointers to corresponding nodes in the address treeinformation are associated with a node of “to” to be the lowest layerrelated to “Tokyo-to” and a node of “cho” to be the lowest layer relatedto “Togocho” and they are thus stored.

Similarly, both a name of “Shibuya-ku” and a name of “Shibukawacho” arewords starting with “Shibu”. In this case, there is generated indexinformation having a tree structure in which a first hierarchy is set tobe a root node, a second hierarchy is set to be “Shibu”, a thirdhierarchy is set to be “ya” and “kawa”, and a fourth hierarchy is set tobe “ku” and “cho”. A character of “Shibu” which is common to two wordsis shared by the first hierarchy. The pointers to corresponding nodes inthe address tree information are associated with a node of “ku” to bethe lowest layer related to “Shibuya-ku” and a node of “cho” to be thelowest layer related to Shibukawacho” and they are thus stored.

FIG. 4 is a diagram typically showing a state in which the indexinformation generated by the index information generating unit 13 andthe address tree information generated by the address tree informationgenerating unit 12 are associated with each other by the pointers. Asshown in FIG. 4, the name of “Tokyo-to” in the index information isassociated with the node of “Tokyo-to” in the first hierarchy of theaddress tree information by the pointer. Moreover, the name of“Shibuya-ku” in the index information is associated with the node of“Shibuya-ku” in the second hierarchy of the address tree information bythe pointer.

The processings of the address information input unit 11, the addresstree information generating unit 12 and the index information generatingunit 13 are executed when the application unit 20 is activated, forexample. An example of a time that the application unit 20 is activatedincludes a time that login from the user terminal 30 to the applicationunit 20 is performed. For instance, when the login from the userterminal 30 to the application unit 20 is performed, the database 25outputs the address information and the address information input unit11 inputs the address information as the address information 200. Basedon the address information 200, then, the address tree informationgenerating unit 12 generates the address tree information and stores theaddress tree information in the memory 14, and furthermore, the indexinformation generating unit 13 generates the index information andstores the index information in the memory 14.

Every time the application unit 20 is activated, thus, the address treeinformation and the index information are generated and stored in thememory 14 based on the address information output from the database 25.Consequently, the address tree information and the index information tobe stored in the memory 14 can be the newest information adapted to thenewest address information stored in the database 25. In other words, itis possible to generate the address tree information and the indexinformation corresponding to the address information in the database 25without performing maintenance through a batch processing.

The request acquiring unit 21 of the application unit 20 acquires arequest for executing a desirable application processing from the userterminal 30. Herein, the acquirement request defines execution of somegeographical information processing by using the data stored in thedatabase 25 and visualization and visual display of a result thereof.

Examples of the geographical information processing include a processingfor displaying pin marks in positions on a map corresponding toaddresses based on address information contained in client business carddata stored in the database 25, for example. Moreover, it is alsopossible to perform a processing for totalizing and graphicallydisplaying the number of business cards having addresses in respectiveareas (the number of clients) every area designated on the map based onthe address information contained in the client business card datastored in the database 25. The processing taken as the example is onlyillustrative and the present invention is not restricted thereto.

In order to perform the above geographical information processing byusing map data having no address information, it is necessary to specifythe position on the map corresponding to the address information basedon coordinate information. However, the latitude and longitudeinformation to be the coordinate information are not stored in thedatabase 25 but only the address information is stored as information tobe used for specifying a position. In the present embodiment, when therequest acquiring unit 21 receives a processing request from the userterminal 30, the address information of the database 25 is convertedinto the latitude and longitude information in real time.

In other words, when the request acquiring unit 21 receives theprocessing request from the user terminal 30, that is, a request forperforming the application processing (the geographical informationprocessing) utilizing the address information over the data stored inthe database 25 is generated, the latitude and longitude informationacquiring unit 22 acquires the latitude and longitude informationcorresponding to the address information contained in the data in thedatabase 25 which is set to be a processing target depending on thecontent of the processing request by referring to the address treeinformation stored in the memory 14 of the geocoding unit 10.

More specifically, the latitude and longitude information acquiring unit22 first searches corresponding nodes in the address tree information inaccordance with the pointers indicated as the index information byreferring to the index information based on the address informationcontained in the data in the database 25 which is set to be theprocessing target. For example, if the address information of the datawhich is set to be the processing target is “. . . Shibuya-ku,Tokyo-to”, the node of “Tokyo-to” in the second hierarchy of the addresstree information is searched in accordance with the pointer indicated asthe index information about “Tokyo-to” to be a first word of the addressinformation. If the address information of the data to be the processingtarget is “. . . Shibuya-ku”, moreover, the node of “Shibuya-ku” in thethird hierarchy of the address tree information is searched inaccordance with the pointer indicated as the index information about“Shibuya-ku” to be the first word of the address information.

Subsequently, the latitude and longitude information acquiring unit 22sequentially performs a search from the searched node based on the indexinformation toward a low order layer on the basis of the addressinformation contained in the data in the database 25 which is set to bethe processing target and acquires latitude and longitude informationfrom the node of the lowest layer with which the latitude and longitudeinformation is associated. For example, if the node of the “Tokyo-to” inthe second hierarchy is searched based on the index information, thelatitude and longitude information acquiring unit 22 traces, in order,“Shibuya-ku” of the third hierarchy, “Sakuragaokacho” of the fourthhierarchy, “20” of the fifth hierarchy and “1” of the sixth hierarchy inthe address tree information based on the address information of “20-1,Sakuragaokacho, Shibuya-ku, Tokyo-to” which is set to be the processingtarget and thus acquires latitude and longitude information associatedwith a node of “1” of the sixth hierarchy.

In the present embodiment, thus, there is employed a construction inwhich both the address tree information and the index information areconstituted by the tree structure and the nodes having the same name areassociated with each other by the pointers. Consequently, it is possibleto efficiently search a relevant node in the address tree information inaccordance with the pointer indicated as the index information byreferring to the index information having the tree structure based onthe address information. By further searching the address treeinformation of the tree structure from the searched relevant node towardthe low order layer, moreover, it is possible to efficiently acquire thelatitude and longitude information associated with the node of thelowest layer. In addition, these processings can be executed underhigh-speed access to the memory 14. Even if there is no conventionalintermediate table, therefore, the address information stored in thedatabase 25 can be converted into the latitude and longitude informationin a short time.

The processing executing unit 23 performs a predetermined applicationprocessing by using the latitude and longitude information acquired bythe latitude and longitude information acquiring unit 22. Theapplication processing to be performed herein indicates a geographicalinformation processing corresponding to the processing request receivedby the request acquiring unit 21. The processing result transmittingunit 24 transmits a result of the processing executed by the processingexecuting unit 23 to the user terminal 30 and displays the result on ascreen of the user terminal 30. Then, the address tree informationstored in the memory 14 is used as data for reference to convert theaddress information into the latitude and longitude information inexecution of the application processing in the application unit 20.

As described above in detail, in the present embodiment, the addressinformation 200 input to the geocoding unit 10 is converted into thetree structure formed hierarchically in the administrative district andthe address tree information constituted by associating the latitude andlongitude information with at least the nodes of the lowest layer ineach branch of the tree structure is generated, and the address treeinformation thus generated is stored in the high-speed accessible memory14.

According to the present embodiment having such a structure, theinformation to be used for converting the address information into thelatitude and longitude information is not generated in a form of aconventional conversion table obtained by causing each address and eachlatitude and longitude to perform one-to-one correspondence to eachother but a form of the tree structure. For this reason, when actuallyconverting the address information into the latitude and longitudeinformation, it is possible to efficiently search the latitude andlongitude information corresponding to given address informationtherefrom by proceeding a retrieval while tracing the address treeinformation of the tree structure in order from a parent node to a childnode to narrow down a retrieval range. In addition, in the presentembodiment, the address tree information is stored in the high-speedaccessible memory 14. As compared with the related art in which accessis given to a conversion table stored in a disk, therefore, theretrieval can be performed at a high speed.

In the present embodiment, moreover, the index information constitutedby the name to be allocated to each node of each hierarchy in theaddress tree information and each pointer from the each name to eachnode of each hierarchy in the address tree information is generatedbased on the address information 200 input to the geocoding unit 10, andthe index information thus generated is stored in the memory 14. Whenactually converting the address information into the latitude andlongitude information, consequently, it is possible to efficiently finda first node in the execution of the search in the address treeinformation in accordance with the pointer indicated as the indexinformation by first referring to the index information based on theaddress information in the database 25 which is set to be the processingtarget.

From the foregoing, even if the latitude and longitude information isconverted from the address information in the database 25 in real timewhen a request is given from the application unit 20 utilizing thelatitude and longitude information, the conversion can be completed in avery short time. Therefore, it is possible to implement remarkably highresponse performance. Consequently, it is not necessary to previouslygenerate an intermediate table in order to avoid inferiority in aresponse as in the related art. According to the present embodiment,thus, it is possible to perform the conversion from the addressinformation into the latitude and longitude information at a high speedin real time depending on the request given from the application unit 20utilizing the latitude and longitude information without generating theintermediate table requiring the maintenance through the batchprocessing.

Although the description has been given to the example in which theaddress tree information and the index information are generated andstored in the memory 14 in the embodiment, only the address treeinformation may be generated and stored in the memory 14 and theconversion from the address information into the longitude and latitudeinformation may be performed by using only the address tree information.Also in this case, the conversion processing can be performed at a highspeed. However, it is preferable to use the index information in thatthe conversion processing can be performed at a higher speed.

Although the description has been given to the example in which theaddress tree information and the index information are generated fromthe address information in the database 25 and are stored in the memory14 in the activation of the application unit 20 (for example, login) inthe embodiment, moreover, the present invention is not restrictedthereto. For example, the address tree information and the indexinformation may be generated every time the database 25 is edited andupdated contents thereof are stored. Alternatively, the address treeinformation and the index information may be periodically generated at acertain interval while the database 25 is edited.

In addition, the embodiment is only illustrative for concreteness in theexecution of the present invention and the technical scope of thepresent invention should not be thereby construed to be restrictive. Inother words, the present invention can be carried out in variousconfigurations without departing from the gist or main features thereof.

EXPLANATION OF DESIGNATION

10 geocoding unit (address/latitude and longitude converting device)

11 address information input unit

12 address tree information generating unit

13 index information generating unit

14 memory

20 application unit

22 latitude and longitude information acquiring unit

23 processing executing unit

1. An address/latitude and longitude converting device comprising: anaddress information input unit for inputting address information; and anaddress tree information generating unit for converting the addressinformation input by the address information input unit into a treestructure formed hierarchically in an administrative district,generating address tree information obtained by associating latitude andlongitude information with at least a node of the lowest layer in eachbranch of the tree structure, and storing the address tree informationthus generated in a high-speed accessible memory.
 2. Theaddress/latitude and longitude converting device according to claim 1further comprising: an index information generating unit for generatingindex information constituted by each name to be allocated to each nodeof each hierarchy in the address tree information and each pointer fromthe each name to the each node of the each hierarchy in the address treeinformation and storing the index information thus generated in thememory.
 3. The address/latitude and longitude converting deviceaccording to claim 2, wherein the index information is obtained byrepresenting a plurality of names to be allocated to the respectivenodes of the respective hierarchies as a tree structure formedhierarchically character by character and associating the pointer with anode of the lowest layer in each branch of the tree structure.
 4. Ageographical information system including a geocoding unit forconverting address information into latitude and longitude informationand an application unit for performing a predetermined applicationprocessing by using the latitude and longitude information converted bythe geocoding unit, the geocoding unit comprising: an addressinformation input unit for inputting the address information; and anaddress tree information generating unit for converting the addressinformation input by the address information input unit into a treestructure formed hierarchically in an administrative district,generating address tree information obtained by associating latitude andlongitude information with at least a node of the lowest layer in eachbranch of the tree structure, and storing the address tree informationthus generated in a high-speed accessible memory, and the applicationunit comprising: a latitude and longitude information acquiring unit forreferring to the address tree information stored in the memory when arequest for performing the predetermined application processing isgenerated, thereby obtaining the latitude and longitude informationcorresponding to address information contained in data which is set tobe a processing target depending on the content of the request; and aprocessing executing unit for performing the predetermined applicationprocessing by using the latitude and longitude information acquired bythe latitude and longitude information acquiring unit.
 5. Thegeographical information system according to claim 4, wherein thegeocoding unit further comprises an index information generating unitfor generating index information constituted by each name to beallocated to each node of each hierarchy in the address tree informationand each pointer from the each name to the each node of the eachhierarchy in the address tree information and storing the indexinformation thus generated in the memory, and the latitude and longitudeinformation acquiring unit refers to the index information based on theaddress information contained in the data which is set to be theprocessing target, thereby searching a relevant node in the address treeinformation in accordance with a pointer indicated as the indexinformation and further searching the address tree information from therelevant node toward a low order layer to obtain the latitude andlongitude information from a node with which the latitude and longitudeinformation is associated.
 6. The geographical information systemaccording to claim 5, wherein the index information is obtained byrepresenting a plurality of names to be allocated to the respectivenodes of the respective hierarchies as a tree structure formedhierarchically character by character and associating the each pointerto a node of the lowest layer in each branch of the tree structure. 7.The geographical information system according to claim 5, whereinprocessings of the address information input unit, the address treeinformation generating unit and the index information generating unitare executed when the application unit is activated.
 8. The geographicalinformation system according to claim 6, wherein processings of theaddress information input unit, the address tree information generatingunit and the index information generating unit are executed when theapplication unit is activated.